I have a Cal Spa 3 years old and I get the error message "sensors out of balance". I replaced the sensors and everything was fine for about 2 months. Now when I turn the tub on it shuts down and again I get the error code, "sensors out of balance." How do I fix this?

If both the spa high limit sensor and the spa temperature sensor have been replaced then you can turn the breaker off on the spa try disconnecting both sensors and reconnecting and then turn the breaker back on and see if it will reset. If the sensors are not causing the problem then it may be the spa circuit board.